Investigations of the excitation energy transport mechanism in donor-acceptor systems

Abstract

Measurements of fluorescence quantum yield ηD/ηoD of Na-fluorescein (donor; D) versus concentration of rhodamine B (acceptor; A) in viscous solutions have been carried out. The donor concentration in these solutions was as follows:C D=2·10(-2) M (system I), 1.5·10(-2) M (II), 10(-2) M (III), 3·10(-3) M (IV), and 5·10(-5) M (V). The experimental results have been compared with current theories of nonradiative electronic energy transfer (NEET). In the case of very strong migration (systems I, II, and III), a significant influence of correlations (between configurations of D and A molecules in the surroundings of successively excited donors) on quantum yield ηD/ηoD has been determined. Experimental values have been found to be clearly higher in comparison with those predicted theoretically. The influence of possible factors on the decrease in the effectiveness of excitation energy transport to traps-acceptors in systems of very strong migration has been discussed.

Highly sensitive and selective fluoride detection in water through fluorophore release from a metal-organic framework

“…2) is caused by the well-known concentration- or self-quenching-effect of fluorescent dyes like fluorescein3031, or by interactions of fluorescein either with aromatic groups of the linker molecules, the metal centers, or the amino groups inside the MOF. Inspired by this observation, we developed the novel MOF-based fluoride sensing concept using the selective release of the fluorescent dye: Since the framework is not connected by strong covalent bonds, it can be broken up under mild conditions by other, more strongly coordinating ligands for the respective metal.…”

Advances in Surface-Enhanced Fluorescence

“…This process was frequently studied by decreases in the quantum yield and polarization or anisotropy of viscous solutions with high probe concentrations [33][34][35][36][37][38]. In the case of fluorescein, the Forster distance for homoRET is about 42 Å [39].…”

Release of the self-quenching of fluorescence near silver metallic surfaces

“…Fitting to the multiexponential model was performed as described previously [19,20]. The contribution of each component to the steady state intensity is given by (2) where the sum in the denominator is over all the decay times and amplitudes. The mean decay time is given by (3) The amplitude-weighted lifetime is given by (4)…”

“…Additionally, the intensity decay becomes more heterogeneous, as can be seen from the need for these decay times to fit the data (Table 1). Fluorescence depolarization is one of the most reliable indicators of homo transfer [1][2][3][4][5][6]. Fig.…”

“…1 These traps act as a "sink" for the excited state energy.Self-quenching of fluorescein and other xantene-type dyes is one of the oldest observations in fluorescence spectroscopy and is due to resonance energy transfer between fluorescein molecules (homo RET). This process was frequently studied by decreases in the quantum yield and polarization or anisotropy of viscous solutions with high probe concentrations [1][2][3][4][5][6]. In the case of fluorescein the Forster distance for homo RET is about 42Å [7].…”